THERMAL SIMULATION STUDY OF CRUDE OIL FROM WELL S74 IN THE TARIM BASIN(Ⅰ)-GEOCHEMICAL CHARACTERISTICS OF THE SIMULATION PRODUCTS

A thermal simulation experiment of the heavy crude oil from Well S74 in the Tarim Basin has been conducted.The hydrocarbon families and the isotopes of the crude oil,the residual extract and the expelled oil have been analyzed.The saturated hydrocarbons have been detected by gas chromatography and gas chromatography-mass spectrometry,and the carbon isotope analysis of the alkane gases has been carried out.The results indicate that: 1) The compositional structure of the saturated hydrocarbons and the biomarkers of sterane and terpane of the residual extract change significantly with the increase of the simulation temperature,whereas the compositional structure of the saturated hydrocarbons and the biomarkers of sterane and terpane of the expelled oil do not change so significantly with the simulation temperature,except at 350 ℃ where anomalies occur.2) The carbon isotopes of the residual extract and its fractions increase gradually with the simulation temperature,whereas those of the expelled oil do not change so regularly with the simulation temperature.3) The carbon isotopes of the alkane gases also increase gradually with the simulation temperature,and the carbon isotope values at various simulation temperature points distribute as the normal sequence.